The invention relates to a shaving apparatus having at least one circular cutting unit which comprises an external cutting member and an internal cutting member, which is rotationally drivable with respect to said external cutting member, which internal cutting member is supported on the external cutting member both by an axial and a radial bearing means, the internal cutting member being in axially interlocking engagement with the external cutting member, the internal cutting member and the external cutting member having cooperating cutting edges for severing hairs, and the shaving apparatus further having a motor provided with a drive member for driving the internal cutting member.
Such a shaving apparatus is known from EP-A2-0 074 684. For the correct cutting of hairs it is necessary that the so-called cutting gap between the cooperating edges of the internal cutting member and the external cutting member is as small as possible. Until now this was achieved by also subjecting the drive member for rotationally driving the internal cutting member to a spring load in an axial direction. As a result of this, the internal cutting member engages against the external cutting member under a given pre-load, i.e. the cutting edges of the internal cutting member are urged against the cutting edges of the external cutting member with a given force. This was necessary because the cutting forces produced during hair cutting are directed in such a way that the cooperating cutting edges tend to be moved apart. The spring load of the cutting member prevents the gap between the cutting edges from becoming too large during cutting. However, this spring load also produces a comparatively high friction between the cooperating cutting edges. In order to reduce this friction EP-A2-0 074 684 proposes to provide the internal cutting member with an axial bearing surface which cooperates with an axial bearing surface of the external cutting member. Thus, it is achieved that the axial spring load of the drive member is transmitted to the external cutting member via these axial bearing surfaces, which is deemed to result in a minimal cutting gap. In the example shown in FIG. 6 of EP-A2-0 074 684 the internal cutting member engages in the external cutting member in an interlocked fashion. Since the drive member also transmits an axial force to the external cutting member via the internal cutting member, the internal cutting member also engages non-positively with the external cutting member. The axial force still causes a frictional loss via the bearing surfaces, particularly because the frictional forces at the cooperating cutting edges lie at a comparatively large distance from the axis of rotation and thus give rise to a loss of torque.